Which one of the following anions is present in chain structure silicates?

(a) ${\mathrm{Si}}_2{\mathrm{O}}_7^{6-}$                 (b) $({\mathrm{Si}}_2{\mathrm{O}}_5^{2-}{)}_{\mathrm{n}}$

(c) $({\mathrm{Si}}_2{\mathrm{O}}_6^{4-}{)}_{\mathrm{n}}$               (d) ${\mathrm{SiO}}_4^{4-}$

${\mathrm{BX}}_3+{\mathrm{NH}}_3\stackrel{\mathrm{R}.\mathrm{T}.}{\to }{\mathrm{BX}}_3 .{\mathrm{NH}}_3+$ Heat of adduct formation $\left(∆\mathrm{H}\right)$

The numerical value of $∆\mathrm{H}$ is found to be maximum for :

(1) ${\mathrm{BF}}_3$                               

(2) ${\mathrm{BCl}}_3$

(3) ${\mathrm{BBr}}_3$                             

(4) ${\mathrm{BI}}_3$

Borax is converted into crystalline boron by the following steps:

          $\mathrm{Borax}\stackrel{\mathrm{X}}{\to }{\mathrm{H}}_3{\mathrm{BO}}_3\stackrel{∆}{\to }{\mathrm{B}}_2{\mathrm{O}}_3\underset{∆}{\overset{\mathrm{Y}}{\to }}\mathrm{B}$

X and Y are respectively :

1. HCl, Mg                                 
2. HCl, C
3. C, Al 
4. HCl, Al

The dissolution of $\mathrm{Al}(\mathrm{OH}{)}_3$ in a solution of $\mathrm{NaOH}$ results in the formation of -

1. ${\left[\mathrm{Al}{\left({\mathrm{H}}_2\mathrm{O}\right)}_4{\left(\mathrm{OH}\right)}_2\right]}^{+}$       

2. $\left[\mathrm{Al}{\left({\mathrm{H}}_2\mathrm{O}\right)}_3{\left(\mathrm{OH}\right)}_3\right]$

3. ${\left[\mathrm{Al}{\left({\mathrm{H}}_2\mathrm{O}\right)}_2{\left(\mathrm{OH}\right)}_4\right]}^{-}$     

4. $\left[\mathrm{Al}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6{\left(\mathrm{OH}\right)}_3\right]$

Choose the correct squence for the geometry of thr given molecules Borazone, Borazole, ${\mathrm{B}}_3{\mathrm{O}}_6^{3-}, {\mathrm{Fe}}_2{\mathrm{Cl}}_{6,}$ trimer of FCN. ('P' stands for planar and 'NP' stdans for non-planar)

(1) NP, NP, NP, P, P                                 

(2) P, P, NP, NP, P

(3) NP, NP, NP, P, NP                                 

(4) NP, P, P, NP, P

Which of the following oxidation states are the most characteristics for lead and tin respectively?

1. +4, +2                     

2. +2, +4

3. +4, +4                     

4. +2, +2

Name the type of the structure of silicate in which one oxygen atom of [SiO₄]^4- is

shared?

1. Sheet silicate

2. Pyrosilicate

3. three dimensional silicate

4. Linear chain silicate

The number of carbon atoms per unit cell of diamond unit cell is:-

1. 4

2. 8

3. 6

4. 1

The incorrect statement among the following regarding borax is-

1. It is a useful primary standard for titrating against acids. 

2. One molecule of borax contains 4 \(B — O — B\) bonds.

3. Aqueous solution of borax can be used as a buffer.

4. It is made up of two triangular \(BO_{3}\) units and two tetrahedral \(BO_{4}\) units.

It is because inability of ns² electrons of the valence shell to participate in bonding that

1. Sn²⁺ is reducing while Pb⁴⁺ is oxidising agent

2. Sn²⁺ is oxidising while Pb⁴⁺ is reducing agent

3. Sn²⁺ and Pb²⁺ are both oxidising and reducing agent

4. Sn⁴⁺ is reducing while Pb⁴⁺ is oxidising agent